Crude oil will still be a major source of transportation energy in the years to come and will not be easily phased out by the recent shale gas boom largely due to the ever increasing demand for fuel, the lack of sufficient infrastructure and the time and cost associated to convert filling stations to be solely gas operated. Gas is currently quite extensively used as heating means across the world and may in future also become more popular as electricity generating means via gas turbines with a lower carbon dioxide footprint than when burning coal, rather than solely be used as a fuel or fuel pre-cursor. This means that the recovery of oil from oil deposits will remain and possibly even become an even more important activity for many years to come.
When using primary and secondary petroleum recovery techniques only around 50% of crude oil in wells can be recovered. During high oil price cycles it pays to explore tertiary recovery methods through the use of chemical surfactants to flood dormant or new wells. This recovery technique is also called enhanced oil recovery (EOR). Together with the need for EOR chemicals in potentially large volumes comes the need for oilfield solvents or drilling fluids. Together, these solvents, drilling fluids and the like are often referred to as oilfield hydrocarbons.
Oilfield hydrocarbons, as well as lubricant base oils, may provide attractive profit margins over fuels if they can be sourced from one single production facility. Such a production facility may advantageously be a Fischer-Tropsch synthesis plant with the required oilfield hydrocarbon molecules and/or base oil molecules present in product streams emanating from a Fischer-Tropsch hydrocarbon synthesis reactor. Typically however, a Fischer-Tropsch plant with its downstream work-up facilities is not configured for production of oilfield hydrocarbons, or for optimised production of lubricant base oils, but rather for production of fuel such as diesel and petrol (gasoline).
EOR chemicals or surfactant feedstock are typically olefins and are those hydrocarbons, once fully functionalized, that get used for the exploration and/or recovery of oil and gas from underground reservoirs. Oilfield solvents are either paraffins or olefins that are used in on-shore or off-shore drilling applications.
The most versatile source of hydrocarbon feedstock for EOR surfactants or chemicals is thus olefins. Olefins are more reactive than paraffins and can therefore be the ideal pre-cursor for alcohols (through e.g. hydroformylation) and alkyl or di-alkyl aromatics (through e.g. alkylation) which can either undergo alkoxylation, sulfation and/or sulfonation to be finally used as linear and/or branched surfactants in EOR applications. An olefin feedstock can also be directly sulfonated to be used in EOR applications either as internal olefin sulfonate or alpha olefin sulfonate. The sources of hydrocarbon feedstock for oilfield solvents and more specifically oil-based drilling fluids are either paraffins or olefins and more preferably a mixture of linear and branched paraffins or internal olefins.
The carbon ranges for oilfield hydrocarbons can vary depending on whether paraffins or olefins are to be used in the various applications. When paraffins and/or olefins are used as a drilling fluid the carbon range could be between C12-C22. Where olefins are used for alkylation to produce alkyl aromatics the carbon range could be C10-C24 and when olefins are used as is or as an alcohol pre-cursor the carbon range could be C16-C30. When the paraffins are used as lubricant base oil the carbon range could be between C18-C55.